Catalytic conversion of hydrocarbons



Dec- 30, 1941- c. 1 THOMAS E -r AL 2,267,766

v CATLYTIG` CONVERSION OF HYDROCARBONS Filed Aug. 21, 1939 "9 J0 4 l rac/ahy .j`zep Zd /l l f7.5

l JZ, v l -f4 f5 T azazQJ/egiwz Poly/,zergaz'zozz l v I' l -f' L5 l fla Gasoline A Pol zer Storage l .5 orage f 7 L9l Patented Dec. 30, 1941 CATALYTIC CONVERSION OF HYDROCABBONS Charles L. Thomas and Herman S. Bloch, Chicago, Ill., assignors to Universal Oil Products Company, Chicago, Ill., a corporation of Delaware Application August 21, 1939, serial Ne. 291,197

1 Claim.

This invention relates to a process for converting hydrocarbon oils into substantially saturated motor fuels. More particularly, the process relates to the catalytic conversion of hydrocarbon oils of boiling range higher than gasoline. A1- though the source of hydrocarbon oil converted according to the present process is usually crude petroleum oil, similar oils from other suitable sources such as shale oil, coal tar, etc., may be used.

The motor fuels produced according to the present invention may be used in any internal combustion engine, but they are particularly suitable for use in airplane motors because of their good antiknock properties, particularly in regard to improvement in octane number upon the addition of tetraethyl lead, and because they are substantially olefin-free and meet the strict specifications applied to this type of fuel by the aviation industry.

A number of processes have been developed to wherein hydrocarbon oils are contacted with suitable catalytic masses and converted into increased yields of motor fuels having better antiknock properties than is usually economically obtainable by the non-catalytic thermal process. Various other types of processes, including poly- In a similar fashion, naph-4 merization of olefins, alk'ylation of parains or aromatics with oleiins, etc., have been developed for use in conjunction with these methods to improve the properties of the ynished gasoline and increase the yields of motor fuel obtainable.

It is with improvements in the method of catalytically converting hydrocarbon oils into premium grade motor fuels particularly suitable for use as aviation base fuels that the present invention is concerned.

In one specific embodiment the presentinvention comprises mixing hydrocarbon oil with oleiin-containing Igasoline such as may be produced by the catalytic or non-catalytic cracking or rell'orming of hydrocarbon. oils, contacting the mixture with a catalytic mass in a primary conversion step at a temperature within the range of approximately 600900 F. and a pressure of substantially atmospheric to 41000 pounds per e square inch, separating the gasoline `and gas, recycling a portion 'of the insuiiiciently converted oilI to a secondary conversion step wherein it is converted into substantial quantities of olefincontaining gasoline and gas at a temperature within the range of approximately 8001200 F. and a pressure of substantially atmospheric to 2000r pounds persquare inch, passing the reaction products to a fractionation step, recycling a portion of the insuiiiciently converted oil, separating olefin-containing gasoline, mixing said gasoline with the original oil charge and passing the mixture to the primary conversion step as previously described, recovering the gases from the secondary conversion step, subjecting them to catalytic polymerization under conditions whereby the olefins are converted to substantially liquid polymer, combining the liquid polymer with the olefin-containing gasoline and the original hydrocarbon oil charge, and passing the mixture to the primary conversion step.

The catalysts which are useful in the present process may include cracking catalysts of various types, such as synthetic precipitated composites consisting essentially of a major portion of precipitated silica having added thereto relatively minor portions of precipitated refractory oxidesv to form masses consisting of silica-alumina, silnation,"` Generally speaking, however, all these components indicate more or less low lcatalytic activity, individually, but in the aggregate display high activity. This activity is not an additive function, it being relatively constant for a wide range of proportions of the components,

whether `in molecular or fractionsv ofl molecular proportions. No one component can be determined` ,as' the one for which the remaining components may be considered as the promoters accordlng to conventional terminology. nor can any According to the description of the prepara` tion of the preferred catalysts given below, precipitated hydrated alumina and/or hydrated zirconia are composited with precipitatedfhydrated silica gel, otherwise known as silica hydrogel, and then the composite is washed, dried, and calcined, producing a catalytic mass. However, the diierent catalystswhich may be so produced therefrom do not necessarily give exactly equivalent results. v

The cracking step whereby the olefin-containing gasolineis produced may consist off any suitable catalytic or non-catalytic processfrom which gasoline of high anti-knock value and containing substantial quantities -oi olefin hydrocarbons may be produced. When using a catalytic cracking step, catalysts similar to those describedk in the foregoing description .may be used, although other catalysts are also suitable under certain conditions.y These include acidtreated clays, as Well as' oxides of alumina and/or magnesium having deposited thereon, promoting oxides such as chromia, iron, vanadium, tungsten oxide, molybdenum oxide, etc. The preferred catalysts, however, are generally of the type described as'silica-aluriiina', silica-zirconia, and silica-alumina-zirconia. The operating conditions under which the cracking step is carried out is within the range of approximately 800m-17200o F. 'and ypressures of substantially atmospheric to slightly super atmospheric, say of the order of 50-200 pounds per square inch.

Any' suitable type of contacter may be used, including tubes or reaction chambers havingy catalyst particles disposed therein.

When non-catalytic cracking isthe source of olefin-containing gasoline and the gases used in the polymerization step, vany suitable conventional type of non-catalytic thermal cracking processfmay, be used. In general, vthistype of process consists of 'a tubular heater followed by a reaction chamber, a hashing zone, and a fractionation step for the recovery of the reaction products. The thermal non-catalytic, cracking step generally carried out` within the range of approximately 800-1100 F.:and apressure of 100-2000 pounds per square inch. The catalyst employed in the polymerization step for converting normally gaseous olens.finto' iliquid polymer may be the so-called solid phosphoric acid catalyst or sulfuric acid. A` solid phosphoric I acid'catalyst is made by mixing liquid phosphoric acid with kieselguhr or similar suitable silicious material, formingthe mixture into shapes, u'su-.

ally by extrusion methods; drying the shapes,

pounds `per square inch. A

ried outD at av Vtemperature of approximately of 200 80-25,0 F. and-a pressure of the order The catalytic -mvass employedfpr treating the y raw oil-"cracked gasoline-polymer mixture develcracking is used as the source of cracked gasoline.

The accompanying drawingillustrates one embodiment ofthe present invention in diagrammatic fashion. j

Referring to the drawing, the raw oil charge enters the system' through line vI and passes through line 2 to catalytic conversion step 3, wherein it is contacted-with a silica-alumina, silica-zirconia or silica-alumina-zirconia cracking catalyst at a temperature within the range of 600900 F. and a pressure of substantiallyatmospheric to 1000 pounds per square inch. Gaseous products are withdrawn through lines i and 5 to gas storage. Gasoline containing substantially no olens is removed through line 0 to gasoline storage l.. Insufilciently converted oil is passed through lines 8 and 9 to cracking step lll, which. -as previously mentioned, may comprise catalytic ornon-catalytic cracking, A portion of insuiciently converted oil is withdrawn through line il, which joins with line 8 and returned to the cracking step. Another portion of insuiciently converted oil may be Withdrawn through line l2. The gasoline produced in cracking step I0 is removed through line I3 to catalytic conversion step 3. The gaseous hydrocarbons produced irr cracking step I0 are removed through line I4 to polymerization stepA I5 wherein the olens are convertedto liquid polymer. The residual gases are removed through line I6, which joins with line 5. All or apart of the polymer productl may be removed through-line I1, which joins with line I3 and is thus passed to catalytic conversion step 3. If so desired, a. fraction of the liquid polymer such as iso'octene, may bel withdrawn through line I8 to polymer storage AS an alternative, ya part of Ithe original charge may be introduced tocracking step' I0 by way of lines I and 20. f

v'I'he following examples are given to illustratel the practicability and usefulness of the Process, but should not be construed as limiting it to the exact' conditions given therein:

Example. 1

I A Pennsylvania gas oil lof 37.0 A. P. I. gravity step ybeing carried out atga temperature of 7750*.` Etf-- wand 'a pressure of 100 pounds per square inch.

'Mixed with this oil was the catalytically cracked ture conversion steps wa's'asubstantially sodium- Y It'A had an octane, number of-79, which was inops any accumulation of carbonaceousjdeposits 'which interfere with theeetalytie activityl andv must bev removed from time to time. Reactive. tion is suitably carried-fout by heating in the presence of oxygen-containing gas at a temperature of 1000o F. .or higher. 4A similar reactivation method may be carried out ii' catalytic free silica-alumina-zirconia mass. "The substahlI tially olefin-free gasoline of 400 E. end-point was recovered from the low temperature step.

creased to 9 by the 'addition 'thereto of 6 cc. oftetreethyi leed 'pergenons Theltotai yield o'f gasoline amounted to 81% lol? the 'raw oilfcharge. I'he gasoline had a bromine numberof 1,- an y oxygen bomb inductionperiod ini excess of`24 hours, 1 milligram of copper-'dish gum per oc., and a sulfur content of less than 0.01%.4

A Mid-Continent topped crude oil was charged a non-catalytic cracking step as indicated by number Hi` in the accompanying drawing. The cil was converted to gasoline and gas at a temperature of approximately 925 F. and a. pressure of 300 pounds per square inch. A portion of the recycle oil was returned to the rcrackingv step. An overhead distillate including the cracked gasoline was passed to catalytic conversion step 3, which was operated at a temperature of '150 F. and a pressure of 100 pounds per square-inch. The insufiiciently convertedoil was returned to cracking step lll. The gas formed was removed from the system and a substantially olefin-free gasoline was recovered. The process gases from cracking step IU were catalytically polymerized using solid phosphoric acid catalyst. The polymer product was passed rto catalytic conversion stepv 3 where it underwent substantial conver sion to a saturated gasoline of high octane number. \A total yield of 59% ,of gasoline having an octane number of '14 which was increased to 93 by the addition of 6 cc. of tetra-ethyl lead was caemos 3 obtained. The 300 F. end-point fraction of this.

gasoline met aviation speciiications.

We claim as our invention: u

A processfor producing substantially saturated gasoline of high anti-knock value which comprises combining olehic gasoline with hydrocarbon oil heavier than gasoline, subjecting the resultant mixture to the action of a cracking catalyst at a temperature of about 60.0-900" 'F., whereby to produce gasoline Aof low olen con tent,` separating the low olen content gasoline from conversion products heavier than gasoline, cracking at least a portion of said heavier products at higher temperature than is maintained in the mst-mentioned conversion step, `thereby forming olenic gasoline and gas, separating the gasoline and gas and subjecting thus separated gaseous oleiins to polymerization, and supplying resultant polymers and olenic gasoline formed Z0 `by the cracking of said heavier products'to the lS-mentioned Conversion Step.

uCHARLES L THOMAS.

HERMAN s. BLOCH. 

